[PATCH] drm/msm/gpu: Fix crash when throttling GPU immediately during boot

[PATCH] drm/msm/gpu: Fix crash when throttling GPU immediately during boot

[Stephan Gerhold]

There is a small chance that the GPU is already hot during boot. In that
case, the call to of_devfreq_cooling_register() will immediately try to
apply devfreq cooling, as seen in the following crash:

  Unable to handle kernel paging request at virtual address 0000000000014110
  pc : a6xx_gpu_busy+0x1c/0x58 [msm]
  lr : msm_devfreq_get_dev_status+0xbc/0x140 [msm]
  Call trace:
   a6xx_gpu_busy+0x1c/0x58 [msm] (P)
   devfreq_simple_ondemand_func+0x3c/0x150
   devfreq_update_target+0x44/0xd8
   qos_max_notifier_call+0x30/0x84
   blocking_notifier_call_chain+0x6c/0xa0
   pm_qos_update_target+0xd0/0x110
   freq_qos_apply+0x3c/0x74
   apply_constraint+0x88/0x148
   __dev_pm_qos_update_request+0x7c/0xcc
   dev_pm_qos_update_request+0x38/0x5c
   devfreq_cooling_set_cur_state+0x98/0xf0
   __thermal_cdev_update+0x64/0xb4
   thermal_cdev_update+0x4c/0x58
   step_wise_manage+0x1f0/0x318
   __thermal_zone_device_update+0x278/0x424
   __thermal_cooling_device_register+0x2bc/0x308
   thermal_of_cooling_device_register+0x10/0x1c
   of_devfreq_cooling_register_power+0x240/0x2bc
   of_devfreq_cooling_register+0x14/0x20
   msm_devfreq_init+0xc4/0x1a0 [msm]
   msm_gpu_init+0x304/0x574 [msm]
   adreno_gpu_init+0x1c4/0x2e0 [msm]
   a6xx_gpu_init+0x5c8/0x9c8 [msm]
   adreno_bind+0x2a8/0x33c [msm]
   ...

At this point we haven't initialized the GMU at all yet, so we cannot read
the GMU registers inside a6xx_gpu_busy(). A similar issue was fixed before
in commit 6694482a70e9 ("drm/msm: Avoid unclocked GMU register access in
6xx gpu_busy"): msm_devfreq_init() does call devfreq_suspend_device(), but
unlike msm_devfreq_suspend(), it doesn't set the df->suspended flag
accordingly. This means the df->suspended flag does not match the actual
devfreq state after initialization and msm_devfreq_get_dev_status() will
end up accessing GMU registers, causing the crash.

Fix this by setting df->suspended correctly during initialization.

Cc: stable@vger.kernel.org
Fixes: 6694482a70e9 ("drm/msm: Avoid unclocked GMU register access in 6xx gpu_busy")
Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org>
---
 drivers/gpu/drm/msm/msm_gpu_devfreq.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
index 6970b0f7f457c8535ecfeaa705db871594ae5fc4..2e1d5c3432728cde15d91f69da22bb915588fe86 100644
--- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
+++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
@@ -156,6 +156,7 @@ void msm_devfreq_init(struct msm_gpu *gpu)
 	priv->gpu_devfreq_config.downdifferential = 10;
 
 	mutex_init(&df->lock);
+	df->suspended = true;
 
 	ret = dev_pm_qos_add_request(&gpu->pdev->dev, &df->boost_freq,
 				     DEV_PM_QOS_MIN_FREQUENCY, 0);

---
base-commit: 33035b665157558254b3c21c3f049fd728e72368
change-id: 20250428-drm-msm-gpu-hot-devfreq-boot-36184dbc7075

Best regards,
-- 
Stephan Gerhold <stephan.gerhold@linaro.org>

Re: [PATCH] drm/msm/gpu: Fix crash when throttling GPU immediately during boot

[Doug Anderson]

Hi,

On Tue, Apr 29, 2025 at 1:34 AM Stephan Gerhold
<stephan.gerhold@linaro.org> wrote:
>
> There is a small chance that the GPU is already hot during boot. In that
> case, the call to of_devfreq_cooling_register() will immediately try to
> apply devfreq cooling, as seen in the following crash:
>
>   Unable to handle kernel paging request at virtual address 0000000000014110
>   pc : a6xx_gpu_busy+0x1c/0x58 [msm]
>   lr : msm_devfreq_get_dev_status+0xbc/0x140 [msm]
>   Call trace:
>    a6xx_gpu_busy+0x1c/0x58 [msm] (P)
>    devfreq_simple_ondemand_func+0x3c/0x150
>    devfreq_update_target+0x44/0xd8
>    qos_max_notifier_call+0x30/0x84
>    blocking_notifier_call_chain+0x6c/0xa0
>    pm_qos_update_target+0xd0/0x110
>    freq_qos_apply+0x3c/0x74
>    apply_constraint+0x88/0x148
>    __dev_pm_qos_update_request+0x7c/0xcc
>    dev_pm_qos_update_request+0x38/0x5c
>    devfreq_cooling_set_cur_state+0x98/0xf0
>    __thermal_cdev_update+0x64/0xb4
>    thermal_cdev_update+0x4c/0x58
>    step_wise_manage+0x1f0/0x318
>    __thermal_zone_device_update+0x278/0x424
>    __thermal_cooling_device_register+0x2bc/0x308
>    thermal_of_cooling_device_register+0x10/0x1c
>    of_devfreq_cooling_register_power+0x240/0x2bc
>    of_devfreq_cooling_register+0x14/0x20
>    msm_devfreq_init+0xc4/0x1a0 [msm]
>    msm_gpu_init+0x304/0x574 [msm]
>    adreno_gpu_init+0x1c4/0x2e0 [msm]
>    a6xx_gpu_init+0x5c8/0x9c8 [msm]
>    adreno_bind+0x2a8/0x33c [msm]
>    ...
>
> At this point we haven't initialized the GMU at all yet, so we cannot read
> the GMU registers inside a6xx_gpu_busy(). A similar issue was fixed before
> in commit 6694482a70e9 ("drm/msm: Avoid unclocked GMU register access in
> 6xx gpu_busy"): msm_devfreq_init() does call devfreq_suspend_device(), but
> unlike msm_devfreq_suspend(), it doesn't set the df->suspended flag
> accordingly. This means the df->suspended flag does not match the actual
> devfreq state after initialization and msm_devfreq_get_dev_status() will
> end up accessing GMU registers, causing the crash.
>
> Fix this by setting df->suspended correctly during initialization.
>
> Cc: stable@vger.kernel.org
> Fixes: 6694482a70e9 ("drm/msm: Avoid unclocked GMU register access in 6xx gpu_busy")
> Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org>
> ---
>  drivers/gpu/drm/msm/msm_gpu_devfreq.c | 1 +
>  1 file changed, 1 insertion(+)

Thanks!

Reviewed-by: Douglas Anderson <dianders@chromium.org>

Re: [PATCH] drm/msm/gpu: Fix crash when throttling GPU immediately during boot

[Konrad Dybcio]

On 4/29/25 10:33 AM, Stephan Gerhold wrote:
> There is a small chance that the GPU is already hot during boot. In that
> case, the call to of_devfreq_cooling_register() will immediately try to
> apply devfreq cooling, as seen in the following crash:
> 
>   Unable to handle kernel paging request at virtual address 0000000000014110
>   pc : a6xx_gpu_busy+0x1c/0x58 [msm]
>   lr : msm_devfreq_get_dev_status+0xbc/0x140 [msm]
>   Call trace:
>    a6xx_gpu_busy+0x1c/0x58 [msm] (P)
>    devfreq_simple_ondemand_func+0x3c/0x150
>    devfreq_update_target+0x44/0xd8
>    qos_max_notifier_call+0x30/0x84
>    blocking_notifier_call_chain+0x6c/0xa0
>    pm_qos_update_target+0xd0/0x110
>    freq_qos_apply+0x3c/0x74
>    apply_constraint+0x88/0x148
>    __dev_pm_qos_update_request+0x7c/0xcc
>    dev_pm_qos_update_request+0x38/0x5c
>    devfreq_cooling_set_cur_state+0x98/0xf0
>    __thermal_cdev_update+0x64/0xb4
>    thermal_cdev_update+0x4c/0x58
>    step_wise_manage+0x1f0/0x318
>    __thermal_zone_device_update+0x278/0x424
>    __thermal_cooling_device_register+0x2bc/0x308
>    thermal_of_cooling_device_register+0x10/0x1c
>    of_devfreq_cooling_register_power+0x240/0x2bc
>    of_devfreq_cooling_register+0x14/0x20
>    msm_devfreq_init+0xc4/0x1a0 [msm]
>    msm_gpu_init+0x304/0x574 [msm]
>    adreno_gpu_init+0x1c4/0x2e0 [msm]
>    a6xx_gpu_init+0x5c8/0x9c8 [msm]
>    adreno_bind+0x2a8/0x33c [msm]
>    ...
> 
> At this point we haven't initialized the GMU at all yet, so we cannot read
> the GMU registers inside a6xx_gpu_busy(). A similar issue was fixed before
> in commit 6694482a70e9 ("drm/msm: Avoid unclocked GMU register access in
> 6xx gpu_busy"): msm_devfreq_init() does call devfreq_suspend_device(), but
> unlike msm_devfreq_suspend(), it doesn't set the df->suspended flag
> accordingly. This means the df->suspended flag does not match the actual
> devfreq state after initialization and msm_devfreq_get_dev_status() will
> end up accessing GMU registers, causing the crash.
> 
> Fix this by setting df->suspended correctly during initialization.
> 
> Cc: stable@vger.kernel.org
> Fixes: 6694482a70e9 ("drm/msm: Avoid unclocked GMU register access in 6xx gpu_busy")
> Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org>
> ---

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad